Heretofore, as a method of bringing an unmanned vehicle to its destination along a predetermined movement passage, a guiding method with the aid of dead reckoning is known which is carried out by estimating the existent position of the vehicle with the aid of a moving direction detector and a movement length measuring instrument and then automatically steering the vehicle so as to pass through previously designated passing points on a predetermined passage. A drawback inherent to this method consists in that there occurs an error in respect of an estimated position of the vehicle due to ruggedness on the road surface or slippage of the vehicle, resulting in the vehicle failing to exactly pass through the predetermined passing points. Accordingly, in order to obviate the above-mentioned drawback, there have been already made various proposals as noted below as to a method of placing suitable ground marks on the movement passage in a spaced relation and intermittently correcting the estimated position of the vehicle by detecting the ground marks from the vehicle side.
(1) For instance, Japanese patent application No. 204915/1982 discloses a technical concept that a light reflector is disposed on the side surface of an object serving as a target, a light emitting element and a light receiving element constituting one pair are mounted on an unmanned vehicle and the latter is caused to turn about a fixed point located in the proximity of the aforesaid target until the vehicle assumes a posture at which the light receiving element receives the highest intensity of light from the light reflector whereby a posture of the vehicle is controlled properly.
(2) Further, Japanese patent application No. 199007/1982 proposes another technical concept that a plurality of environmental matters such as wood, building or the like are utilized as marks for measuring not only the position of an unmanned vehicle but also the position of a manned vehicle.
However, the method as disclosed in the above item (1) fails to detect the ground marks due to disturbance during movement of the unmanned moving vehicle because a sensor adapted to detect the ground marks has a narrow detection range. Also, the method as proposed in the item (2) has problems that means for discriminating the environmental matter such as wood, building or the like requires a remarkably high production cost and therefore the method can not be put in practical use at present.
The present invention has been made with the foregoing background in mind and its object resides in providing an apparatus for guiding the movement of an unmanned body which assures that the position of the unmanned moving body can be exactly corrected at a lower cost.